Field of the Invention
The present invention relates to an isostatic breaking strength tester and an isostatic breaking strength test method. To be more specific, the invention relates to an isostatic breaking strength tester and an isostatic breaking strength test method that pressurize a part of a ceramic honeycomb structure up to pressure test strength and enable a total inspection of isostatic breaking strength in a process of manufacturing the ceramic honeycomb structure.
Description of the Related Art
Conventionally, measurement has been performed regarding isostatic breaking strength (hereinafter, referred to simply as the “breaking strength”) which indicates strength against isotropic external pressure of a ceramic honeycomb structure (hereinafter, referred to simply as the “honeycomb structure”) which includes partition walls defining a plurality of cells extending from one end face and the other end face and a circumferential wall provided around the partition walls. The breaking strength is measured to guarantee whether the honeycomb structure has sufficient strength for practical use when it is used in various applications such as a filter member and a heat exchange member, and the breaking strength is employed as one of quality determination criteria to ship the honeycomb structure as a product with breaking strength (a pressure test strength or a guarantee strength) equal to or greater than a reference value.
The breaking strength of the honeycomb structure is measured mainly on the basis of a breaking strength test method stipulated in car standard (JASO M505-87) issued by the Society of Automotive Engineers of Japan. The breaking strength test method is described in detail. A honeycomb structure is clamped with aluminum plates to cover the both end faces, and further wrapped with elastic material such as rubber around a circumferential wall. The honeycomb structure is then submerged and set in a pressure container (a submersion isostatic breaking strength tester) filled with water, and subject to isotropic pressure as water pressure inside the container gradually increases. As the water pressure inside the container gradually increases, the pressure is applied from the periphery of the submerged honeycomb structure, and eventually, a breakage occurs on the partition wall or the circumferential wall of the honeycomb structure. A value of pressure at which the breakage occurs (breaking strength) is measured.
In the above-described breaking strength test method, the preparation before setting the honeycomb structure inside the pressure container is complicated, and those operations take a lot of time in some cases. In addition, since the honeycomb structure is submerged inside the container and is subjected to the pressurization until it breaks, it is difficult for the honeycomb structure used for the measurement to be shipped as a product. Thus, inspections are usually carried out by visually observing the external appearance of the honeycomb structure and the above-described breaking strength test is carried out if it is necessary. Therefore, it is difficult to perform a total inspection of the breaking strength in the process of manufacturing the honeycomb structure.
Meanwhile, the inventors of the present application or the like have been already proposed a compression tester in which a honeycomb structure is pressurized up to predetermined pressure test strength, maintained at the pressure test strength for a certain period of time, and then inspected whether a breakage occurs on a partition wall or a circumferential wall of the honeycomb structure. Accordingly, it is unnecessary to pressurize the honeycomb structure until it breaks, and thus it is possible to perform a total inspection of the breaking strength in a process of manufacturing the honeycomb structure.
Examples of the above-described compression tester have been proposed such as a tester having a configuration in which “a compression test of a measurement sample is performed by arranging an elastic sleeve around an outer circumferential surface of a ceramic measurement sample (corresponding to the honeycomb structure), installing the sample inside a tubular container with an elastic sheet interposed between the elastic sleeve and the tubular container, and injecting a hydrostatic-pressure pressurization medium between the tubular container and the elastic sheet to pressurize” (see Patent Document 1). Another tester have been proposed in which a configuration of “using rubbery material such that an elastic sheet has a thickness of equal to or less than 5 mm and a hardness of 30 to 50 degree” is further added to the compression tester of Patent Document 1 (see Patent Document 2).
Further, a “strength inspection method and a strength inspection device of a honeycomb structure”, which are capable of easily and suitably inspecting whether the honeycomb structure satisfies a predetermined guarantee strength, have been proposed (see Patent Document 3). According to the strength inspection method and the strength inspection device, there are two or more peaks of inspection pressure distribution in an axial direction on an outer surface of a skin layer of the honeycomb structure, and inspection pressure is loaded on the honeycomb structure such that each inspection capability of valley portions of the peaks becomes equal to or greater than a guarantee strength (guarantee pressure).
The compression tester, the strength inspection device, and the like described above can keep the pressurization up to a predetermined pressure test strength (guarantee strength), and thus, it is possible to perform the total inspection of the honeycomb structure in any case. Further, it is unnecessary to submerge the honeycomb structure inside the container of the pressure container as in the related art, thus it is possible to simplify the preparation and operations before measurement.
[Patent Document 1] JP-A-2001-41867
[Patent Document 2] JP-A-2001-242054
[Patent Document 3] JP-A-2010-121966